Exploring the casque anatomy of aerial jousting helmeted hornbills

New analysis reveals how the stunning inner anatomy of the helmeted hornbill’s casque permits it to face up to harm throughout aerial jousting battles with rivals. Researchers hope that this new understanding might help to preserve this critically endangered species, in addition to present new insights into creating impact-resistant bio-mimetic supplies.

“After I began in Hong Kong, I visited Metropolis College of Hong Kong (HKU)’s conservation forensics group to talk about their analysis and so they launched me to this wonderful chicken, to its weird cranial anatomy, and to the threats posed to the species by the unlawful wildlife commerce,” says Dr. Mason Dean, an Affiliate Professor of Comparative Anatomy at HKU.

The helmeted hornbill (Rhinoplax vigil) is prized within the unlawful wildlife commerce for its bulbous “casque,” a helmet-like protrusion on the entrance of its cranium. Whereas casques are a shared ornamentation amongst hornbills, they appear to play completely different roles for various species. Specifically, whereas the casques of most species are hole, that of the helmeted hornbill is fronted by a thick keratin layer (“hornbill ivory”) and filled with an exceptionally dense community of bone.

“As I discovered extra about this species, I found a cross-section of a dried cranium in a museum, revealing a surprising trainwreck of trabeculae within the casque,” says Dr. Dean. “After I heard that people are identified to ram their casques collectively in mid-air shows, I simply needed to know extra concerning the practical morphology.”

Trabeculae (inter-connected struts inside vertebrate bone) are a method that bones present excessive energy and resistance to buckling, within the locations the place bones want it most.

“Understanding hornbill anatomy and the way it permits for this jousting habits can due to this fact give us clues about this elusive animal’s ecology and elementary elements of its life historical past and well being,” says Dr. Dean.

“Since hornbill practical anatomy is nearly unexplored, our findings will ideally additionally give new views on the bio-inspired design of high-performing composites for tolerating harm from repeated collisions,” Dr. Dean continues. “We’re particularly enthusiastic about the concept the helmeted hornbill might be a mannequin for light-weight impact-resistant supplies, as this might give options for the place administration of collision is significant, from helmets to autos and aerospace rover wheels.”

Dr. Dean and his workforce used microCT to look within the casque’s completely different buildings.

“We have now been targeted on understanding the hierarchical architectures of the cranium, uniting biology, supplies science and engineering methods,” he says. “We have now sufficient samples that we are able to examine men and women, with some specimens that also have joint flexibility, and a few the place the rhamphotheca (the keratin sheath on the casque and mandible) can slide off.”

“As soon as we began the challenge, numerous actually beautiful hornbill lovers got here out of the woodwork to assist,” says Dr. Dean. “We have been in a position to get an in depth and quantitative image of how the casque is constructed, how the bone interacts with the keratin, and the intricate latticework of bone trabeculae supporting the cranium’s affect floor.”

Dr. Dean and his workforce discovered that the hornbill’s trabeculae had been on common as thick or thicker than these in an elephant’s femur, regardless of belonging to a a lot smaller animal—opposite to a standard development of trabeculae scaling with animal dimension.

“I’ve used microCT to take a look at an enormous range of animal skeletons, however I’ve by no means seen bony trabeculae like those we have discovered within the hornbill,” says Dr. Dean.

“That huge stand of trabeculae then channels again to the braincase, like a bundle of banyan tree prop roots, converging on a bony platform that is way more strengthened than in different hornbills and relations we have checked out,” says Dr. Dean. “All of those anatomical options begin to give a way of how the cranium of the helmeted hornbill is tailored to face up to one of many quickest identified organic impacts, the place males butt heads in ‘aerial jousting’ on the velocity of vehicle collisions.”

Because of the unlawful wildlife commerce, particularly in Asia the place Dr. Dean and his workforce work, this species is now Critically Endangered on the IUCN Pink Listing of Threatened Species, with a lot of its unlawful commerce via Hong Kong sure for mainland China.

“The helmeted hornbill is without doubt one of the largest hornbill species in Asia, with the keratin fronting its casque traditionally a goal for the artwork and vintage marketplace for carving into decorative wildlife merchandise,” says Dr. Dean. “A lot of our cranium specimens nonetheless contained the bullets that had probably killed the animal.”

“Because the species is elusive and arduous to watch within the wild, there’s a nice want to enhance data of its biology, to protect its habitat, defend dwindling wild populations, and to develop higher instruments to ID wildlife merchandise,” he provides. “We hope initiatives like ours contribute to an understanding of species’ pure historical past and lift public consciousness of the challenges going through biodiversity loss, whereas additionally ideally exhibiting scientists that steps towards conservation needn’t solely come from conservation biologists.”

This analysis is being introduced on the Society for Experimental Biology Annual Convention in Prague from 2–5 July 2024.